This sort of power supply device automatically identifies the type of a connected LED light output device, and outputs a voltage or a current suitable for the LED light output device. For this reason, a conventional LED light output device is preliminarily given an identifier for indicating the type thereof, and the power supply device is adapted to read the identifier upon connection and identify the type of the LED light output device.
For example, in Patent Literature 1, an LED light output device is added with a resistive element for type identification, and a power supply device reads the value of the resistive element upon connection to identify the type of the LED light output device.
However, such a configuration requires providing an identifier (e.g., the above-described resistive element) on the LED light output device side, and also requires, in addition to an electric power supply cable, a communication cable for reading the identifier as a connection cable between the LED light output device and the power supply device.